#include<iostream>
using namespace std;
const int N=5010;
int a[N][N];
int f[N][N];
int n,m;
int main(){
	cin>>n>>m;
	while(n--){
		int x,y,v;
		cin>>x>>y>>v;
		x++,y++;
		a[x][y]+=v;
	}
	n=5001;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			f[i][j]=f[i-1][j]+f[i][j-1]-f[i-1][j-1]+a[i][j];
		}
	}
	int ret=0;
	m=min(m,n);
	for(int x2=m;x2<=n;x2++){
		for(int y2=m;y2<=n;y2++){
			int x1=x2-m+1;
			int y1=y2-m+1;
			ret=max(ret,f[x2][y2]-f[x1-1][y2]-f[x2][y1-1]+f[x1-1][y1-1]);
		}
	}
	cout<<ret<<endl;
	return 0;
}
